Your sandwich is getting squished because you use a bag

Use a rigid container that’s just slightly bigger than the sandwich, not a plastic bag. The bag is the problem — it offers zero structure, so everything in your lunchbox presses straight down on the bread.

A hard plastic or metal sandwich box with a flat bottom fixes this. You want one that’s about the same footprint as the sandwich, so it can’t slide around and get crushed sideways. Add a small napkin or paper towel on top if the lid touches the bread — that gap is usually enough to keep the top slice from sticking.

If you really want to use a bag, put the sandwich in first, then pack heavier stuff like fruit or a yogurt cup on the side, not on top. But honestly, a dedicated box is cheaper than replacing a sad, flattened sandwich.

Future lunches will be structurally sound.